Fluid sampling apparatus

ABSTRACT

A representative sample of a liquid under elevated pressure and containing at least one component which would be a gas at a lower pressure is obtained by the introduction of a sample thereof at about said elevated pressure into a major cavity section of a sample container. A contaminant-free minor cavity section of said container is separated from said major cavity section by means of a partition which is rupturable at a pressure above said elevated pressure but below the rupture pressure for the remainder of the container.

United States Patent 1191 1111 3,824,858

Erdman July 23, 1974 FLUID SAMPLING APPARATUS 2,659,442 11/1953 Sutliff 166 164 x 2,941,405 6/1960 Southwick 73/421 R [75] Inventor gs Emma, Bartlesvme 3,075,585 1/1963 Carlton et al 166 164 [73] Assignee: Philips Petroleum, Bartlesville, Primary Examiner-Richard C. Queisser Qk1 Assistant ExaminerDaniel M. Yasich [22] F1led: Dec. 13, 1972 ABSTRACT [21] NQ: 314567 A representative sample of a liquid under elevated pressure and containing at least one component which 52 us. (:1. 73/421 R, 73/422 R would boa gas at a lower pressure is obtained y tho 151 Int. Cl. G01n 1/10 introduction of a Sample thereof at about said elevated [58] Field of Search 73/421 R, 422 GC, 425.4 R, P into a major Cavity Section of a Sample 73 421 5 175 30 55 270; 1 1 2 4 tainer. A-contaminant-free minor cavity section of said container is separated from said major cavity sec- [56] R fe Cit d tion by means of a partition which is rupturable at a UNITED STATES PATENTS pressure above said elevated pressure but below the 2 374 227 M1945 Metcalf M21 5 R rupture pressure for the remainder of the container. 2:380:97? 8/1945 Lewis 73/421.5 R I 8Claims,2Drawing Figures 16 inn nil OUTLET nun n1 1" -1o 38 i i 30 Pmcmwmw 3.824.858

SAMPLE SEPARAT0R'1 CONTAINER GAS X H E LIQUID PHASE 24 WWW/A m5 is: E: E

WW ,\A/\/-.- o a a a D FLUID SAMPLING APPARATUS This invention relates to a method of recovering a fluid sample and to an apparatus suited to the practice of said method.

A wide variety of methods are known to the art for the collection of fluid samples commonly referred to as liquids, gases, or mixtures thereof depending upon their form and composition. Prior art methods employed to obtain a sample of the liquid phase of liquid-gas mixtures with no loss of dissolved gas and/or without contaminating the sample with extraneous .substances heretofore have proved to be inconvenient, costly, difficult to perform and do not provide a representative sample of the liquid sample. A major shortcoming of the prior art sampling techniques is the failure of the prior art to employ a suitable sample collection apparatus, e.g., a sample apparatus which provides for the collection of a liquid phase sample which, after the sample is collected, provides a vapor space free of sample contaminants within the container which prevents excessive pressure from developing in said container while collecting, transporting, or recovering the sample from such container for analysis thereof. I-Ieretofore prior art processes such as those described and recommended in American Petroleum Institute publication RP 44, first edition, January 1966, provide for a vapor space within a liquid sample container by displacing from said container an oil-insoluble liquid, such as mercury, brine, glycol-water mixtures or water during collection of the sample. Undesirably, said oil-insoluble liquids often chemically modify the liquid sampled, which prevents accurate geochemical analysis of the liquid sample.

It is an object of this invention to provide a method for collecting a fluid sample corresponding in composition to the fluid sampled. Another object is to provide a method for collecting an oil reservoir fluid corresponding in composition to the oil reservoir fluid sampled. Still another object is to provide an apparatus which will collect a fluid sample from which an arcuate sample analysis can be obtained. Another object is to provide an apparatus which will collect an oil reservoir fluid sample which, in the event of an undesirable pressure buildup within the container during collection, transportation, or recovery of the fluid sample contained therein, provides for the retention of the oil reservoir fluid within the apparatus in an uncontaminated form.

The attainment of the foregoing objects and advantages associated therewith will be readily apparent from the drawings, the disclosure and the appended claims.

In accordance with this invention, a container is'provided for the collection of a fluid sample. The container comprises an inlet-valved passageway and an outletvalved passageway in communication with a major cavity section of the containenA minor cavity section is divided from the major cavity section by a rupturable partition. The minor cavity is connected to an inletoutlet-valved passageway.

The method of this invention provides a sample fluid representative of the fluid sampled wherein the sample fluid is collected, transported and recovered from the container of this invention.

The method and apparatus of this invention will be described in greater detail with reference to the accompanying drawing.

FIG. 1 illustrates by means of a schematic drawing an exemplary method of collecting a representative fluid sample of an oil reservoir according to the practice of this invention. FIG. 2 illustrates, in partial cross section, a preferred sample container employed in the practice of this invention.

Referring now to FIG. I, a sample of oil is recovered from an oil reservoir 2 via well bo're casing 4. The oil sample is then passed to a gas-oil separator 6 via well head conduit 8. The flow of oil from the oil reservoir into separator 6 is suitably regulated so that a gas-liquid phase equilibrium condition exists within the separator at temperatures and pressures which remain constant within the separator. A portion of the liquid oil phase contained within separator 6 is passed to sample container 10 via conduits l2 and 24 while maintaining valve 23 in a closed position and valves l3, l6, l8 and 20 in an open position. The flow of liquid-phase oil through the container 10 is maintained for a sufficient period of time to purge the major cavity section 30 of container 10 (better shown in FIG. 2) of any impurities. The purging of the major container section is carried out while maintaining constant pressure within the inlet-valved passageway 20, the major cavity section 30 and the outlet-valved passageway 18. Upon reaching constant pressure following purging of the major cavity section, outlet passageway valve 18 is closed and inlet passageway 20 is closed under closure conditions which prevent the occurrence of a pressure drop between valve 18 and valve 20. Conduit 14 connected to throttle valve 16 represents a discharge conduit for oil passing to the sample container which is excess to the requirements of the volume of sample required to completely fill the major cavity section during purging or sample collection. After completely filling the major cavity section at constant pressure, sample container 10 can be disconnected from conduit 24 and throttle valve 16 for transportation of the sample container and the fluid contained therein for recovery of the sampled fluid and analysis thereof by conventional geochemical techniques. Referring now to FIG. 2, the apparatus of this invention is further described with respect to an exemplary preferred sample container. Sample container 10 comprises an inlet passageway valve 20 and an outlet passageway valve 18 in communication with major cavity section 30. A minor cavity section 34 is divided from the major cavity section 30 by rupturable partition 36. The major container section 30 communicates with the minor cavity section 34 when partition 36 breaks at rupture pressures lower than the rupture pressure of the rest of the container. In a preferred embodiment, the minor cavity section 34, prior to collection of the liquid oil sample, is purged of any potential oil analysis contaminant, e.g., air, oxygen or any other element or compound which upon contact with the oil sample adversely or deleteriously affects or chemically modifies the composition of the oil sample. An inlet-outletvalved passageway 38 provides access to minor cavity section 34 for purging, evacuating, and pressurizing it with an inert atmosphere. A presently preferred apparatus is the minor cavity section 34 pressurized with an inert gas such as argon, helium or the like prior to collection of the liquid oil sample. A safety blowout plug 40 is located in inlet-valved passageway 20. The blowout plug ruptures or blows out at pressures lower than the rupture strength of the materials employed in the fabrication 'of the sample container.

The use of the apparatus and employment of the method of this invention can be effectively carried out in the procurement of a representative liquid sample from a first stage oil separator wherein the separator is operated at pressures in the range of from 50 to 1,000 psig and temperatures within the range of from slightly below ambient temperature to 350 F. Design parameters for the apparatus employed under the aforesaid sampling conditions preferably comprise an apparatus wherein rupturable partition 36 fails at major cavity section 30 pressures in the range of from 1,400 to 1,600 psig, and wherein blowout plug 40 ruptures at major cavity section 30 pressures in the range of from 2,000 to 3,000 psi. Minor cavity section 34 volume is percent of the volume of major cavity section 30.

The composition of the liquid oil sample obtained from the oil reservoir first stage separator after collection in the apparatus of this invention can be transported safely to a suitable laboratory for recovery of the sample and appropriate geochemical analysis thereof. As is known to those skilled in the art, with knowledge of the temperature and pressure conditions within the first stage separator as well as knowledge of the gas-oil ratio under said temperature and pressure conditions, analysis of individual gas and liquid samples obtained from the separator under the known temperature-pressure conditions permits exact composition computation characterization of petroleum as it exists in the oil reservoir formation sampled.

Reasonable variations and modifications are possible within the scope of this disclosure without departing from the spirit and scope thereof.

What is claimed is:

1. A detachable fluid sampling container apparatus adapted to permit the flow of a fluid therethrough and comprising means defining a major cavity adapted to contain a fluid sample at an elevated pressure, an inlet valve means having an inlet passageway in fluid communication with said major cavity, an outlet valve means having an outlet passageway in fluid communication with said major cavity section, said inlet valve and said outlet valve being adapted to regulate the passage of a fluid to be sampled through said major cavity, means defining a minor cavity with a fluid passageway between said major cavity and said minor cavity, and a rupturable partition characterized by a breaking strength lower than the breaking strength of the remainder of said apparatus, said rupturable partition being positioned in said fluid passageway between said major cavity and said minor cavity to prevent fluid communication between said major cavity and said minor cavity except upon rupture of said partition when the pressure in said major cavity reaches a predetermined value, said minor cavity and said major cavity being adapted to collectively contain said fluid sample upon the rupture of said partition.

2. Apparatus in accordance with claim 1 wherein said major cavity contains a liquid under pressure lower than the breaking strength of the partition, said liquid containing at least one component which would be a gas at a pressure lower than the pressure inside said major cavity.

3. Apparatus in accordance with claim 2, wherein said major and minor cavities contain said liquid under pressure at least equal to the breaking strength of the partition, but lower than the breaking strength of the remainder of the container.

4. Apparatus in accordance with claim 1, wherein said minor cavity contains an inert gas. I

5. Apparatus in accordance with claim 1, wherein the breaking strength of the partition is within the range of from 1,400 to 1,600 psi, and the breaking strength of the remainder of the container is within the range of from 2,000 to 3,000 psi.

6. Apparatus in accordance with claim 1 additionally comprising an inlet-outlet valve means having an inletoutlet passageway in fluid communication with said minor cavity.

7.-Apparatus in accordance with claim 6 wherein said major cavity is in communication with a safety passageway containing a blowout plug, said blowout plug being designed to rupture at a pressure higher than the breaking point of said partition and lower than the breaking point of the remainder of said container apparatus.

8. Apparatus in accordance with claim 7 wherein the breaking strength of said partition is within the range of from 1,400 to 1,600 psi, and the rupture pressure of said blowout plug is within the range of from 2,000 to 3,000 psi. 

1. A detachable fluid sampling container apparatus adapted to permit the flow of a fluid therethrough and comprising means defining a major cavity adapted to contain a fluid sample at an elevated pressure, an inlet valve means having an inlet passageway in fluid communication with said major cavity, an outlet valve means having an outlet passageway in fluid communication with said major cavity section, said inlet valve and said outlet valve being adapted to regulate the passage of a fluid to be sampled through said major cavity, means defining a minor cavity with a fluid passageway between said major cavity and said minor cavity, and a rupturable partition characterized by a breaking strength lower than the breaking strength of the remainder of said apparatus, said rupturable partition being positioned in said fluid passageway between said major cavity and said minor cavity to prevent fluid communication between said major cavity and said minor cavity except upon rupture of said partition when the pressure in said major cavity reaches a predetermined value, said minor cavity and said major cavity being adapted to collectively contain said fluid sample upon the rupture of said partition.
 2. Apparatus in accordance with claim 1 wherein said major cavity contains a liquid under pressure lower than the breaking strength of the partition, said liquid containing at least one component which would be a gas at a pressure lower than the pressure inside said major cavity.
 3. Apparatus in accordance with claim 2, wherein said major and minor cavities contain said liquid under pressure at least equal to the breaking strength of the partition, but lower than the breaking strength of the remainder of the container.
 4. Apparatus in accordance with claim 1, wherein said minor cavity contains an inert gas.
 5. Apparatus in accordance with claim 1, wherein the breaking strength of the partition is within the range of from 1,400 to 1, 600 psi, and the breaking strength of the remainder of the container is within the range of from 2,000 to 3,000 psi.
 6. Apparatus in accordance with claim 1 additionally comprising an inlet-outlet valve means having an inlet-outlet passageway iN fluid communication with said minor cavity.
 7. Apparatus in accordance with claim 6 wherein said major cavity is in communication with a safety passageway containing a blowout plug, said blowout plug being designed to rupture at a pressure higher than the breaking point of said partition and lower than the breaking point of the remainder of said container apparatus.
 8. Apparatus in accordance with claim 7 wherein the breaking strength of said partition is within the range of from 1,400 to 1,600 psi, and the rupture pressure of said blowout plug is within the range of from 2,000 to 3,000 psi. 